1. Field of the Invention
The present invention relates to an overheat preventing unit of a scroll compressor and, more particularly, to a scroll compressor having an overheat preventing unit capable of enhancing reliability of a compressor and protecting the compressor by bypassing a high temperature and high pressure gas of a high pressure chamber to a low pressure chamber when internal temperature of the compressor goes beyond a pre-set temperature.
2. Description of the Background Art
In general, various types of compressors can be employed according to a compression method, and for an air-conditioner that requires a small and light compressor, a scroll compressor is commonly used.
FIG. 1 is a sectional view of a scroll compressor in accordance with a conventional art.
The conventional scroll compressor includes: a casing 106 having a certain closed space, to which a suction pipe 102 for sucking a fluid and discharge pipe 104 for discharging a compressed fluid are connected, a driving unit 108 disposed at a lower portion of the casing 106 and generating a driving force; and a compressing unit 110 disposed at an upper portion of the casing 106 and connected to the driving unit 108 by a rotating shaft 112 to compress the fluid sucked into the suction pipe 102 according to rotation of the rotating shaft 112 and discharge it through the discharge pipe 104.
A main frame 114 for rotatably supporting the upper portion of the rotating shaft 112 and the compressing unit 110 is installed at the upper portion of the casing 106, and a lower frame 116 for rotatably supporting a lower portion of the rotating shaft 112 is installed at the lower portion of the casing.
The driving unit 108 includes a stator 122 fixed in a circumferential direction of the casing 106 and a rotor 124 disposed at an inner circumferential surface of the stator 122 and fixed at the rotating shaft 112. When power is applied to the stator 122, the rotor 124 is rotated according to interaction between the stator 122 and the rotor 124, rotating the rotating shaft 112.
The compressing unit 110 includes a fixed scroll 128 having a fixed wrap 126 in an involute shape and fixed at an upper portion of the casing 106, and a orbiting scroll 132 having an orbiting wrap 130 in the involute shape corresponding to the fixed wrap 126 to have a certain compression chamber 118 therebetween, orbitally supported by the main frame 114, and orbiting when the rotating shaft 112 is rotated.
A discharge passage 136 is formed at the center of the fixed scroll 128 in order to discharge a fluid after being compressed in the compressing chamber 118 according to the interaction between the fixed wrap 126 and the orbiting wrap 130, and a chuck valve 138 is installed at an upper side of the discharge passage 136 in order to prevent backflow of discharged fluid.
A muffler 140 is mounted at an upper side of the fixed scroll 128 in order to reduce noise of a gas being discharged to the discharge passage 136, and an oldhamring 150 for preventing rotation of the orbiting scroll 132 is installed between the orbiting scroll 132 and the main frame 114.
A temperature sensor (not shown) for sensing a temperature of a gas is installed at the discharge pipe 104 which is connected in or to a high pressure chamber 142 into which a compressed gas flows after being formed by the muffler 140 and discharges the compressed gas. Thus, when a temperature inside the high pressure chamber 142 goes up beyond a pre-set value, the temperature sensor cuts off power being applied to the compressor to protect the compressor.
As mentioned above, the conventional scroll compressor operates as follows. That is, when power is applied to the stator 122, the rotor 124 is rotated according to interaction between the stator 122 and the rotor 124 and the rotating shaft 112 fixed at the rotor 124 is rotated in a forward direction. Then, the orbiting scroll 132 is orbitally moved according to the rotation of the rotating shaft 112 to interact with the fixed scroll 128 to compress the gas flowing into the compressing chamber 118. The compressed gas is introduced into the high pressure chamber 142 through the discharge passage 136, and then the gas introduced into the high pressure chamber is discharged externally through the discharge pipe 104.
At this time, the fluid discharged toward the high pressure side through the discharge passage 136 is prevented flowing back to the lower pressure side by the chuck valve 138.
However, because the conventional scroll compressor must include an electric circuit such as a temperature sensor for sensing the temperature of the high pressure chamber, fabrication cost increases. In addition, after the temperature of the high pressure chamber is sensed by the temperature sensor, driving of the compressor is stopped, causing a problem that operation delay may occur or malfunction is generated to damage the compressor.